The USDA issued a new federal order on Friday, Dec. 6, that requires raw (unpasteurized) milk samples nationwide be collected and shared with the USDA to test for the prevalence of highly pathogenic avian influenza (HPAI) H5N1.
The National Milk Testing Strategy (NMTS) was developed with significant input from state, veterinary and public health stakeholders to facilitate a comprehensive H5N1 surveillance of dairy herds, monitor trends and help contain any potential spread of the virus.
“Since the first HPAI detection in livestock, USDA has collaborated with our federal, state and industry partners to swiftly and diligently identify affected herds and respond accordingly. This new milk testing strategy will build on those steps to date and will provide a roadmap for states to protect the health of their dairy herds,” said Secretary of Agriculture Tom Vilsack.
There are three requirements in the new federal order:
- It requires the sharing of raw milk samples, upon request, from any entity responsible for a dairy farm, bulk milk transporter, bulk milk transfer station or dairy processing facility that sends or holds milk intended for pasteurization.
- Herd owners with positive cattle are required to provide epidemiological information that enables activities such as contact tracing and disease surveillance.
- It requires that private laboratories and state veterinarians report positive results to the USDA that come from tests done on raw milk samples drawn as part of the NMTS.
The dairy industry is reminded that the USDA’s April 24 federal order that requires the mandatory testing of lactating dairy cows prior to interstate shipment and requires that all privately owned laboratories and state veterinarians report positive test results connected with those tests is still in place. The new federal order does not override it but is intended to complement and enhance the existing order.
Strategy outlined
Six states were identified as part of the first round of states brought into the program for testing. They are California, Colorado, Michigan, Mississippi, Oregon and Pennsylvania.
California is currently the only state with new confirmed cases of HPAI in dairy cattle in the last 30 days (with a total of 506 herds since late August). Since the outbreak began, Colorado has had 64 affected herds and Michigan had 29 affected herds. Mississippi, Oregon and Pennsylvania have not had any detections to date. However, Pennsylvania, along with Colorado and Michigan, has already implemented a milk testing program.
The first round of silo testing is scheduled to begin the week of Dec. 16 for states not already testing.
Additional states will be included in the coming weeks in ways that meet the needs of each state and the importance of the response until each of the 48 contiguous states are participating in the program.
Once a state begins testing under the NMTS, the USDA’s Animal and Plant Health Inspection Service (APHIS) will place that state into one of five stages based on the HPAI H5N1 virus prevalence in that state.
Stage 1: Standing up mandatory USDA national plant silo monitoring
The USDA will immediately begin nationwide testing of milk silos at dairy processing facilities. This national sample will allow the USDA to identify where the disease is present, monitor trends and help states identify potentially affected herds.
Stage 2: Determining a state’s H5N1 dairy cattle status
Building on the results of silo monitoring, in collaboration with states, the USDA will also stand up bulk tank sampling programs in order to identify herds in the state that are affected with H5N1.
Stage 3: Detecting and responding to the virus in affected states
For states with H5N1 detections, APHIS will work quickly to identify specific cases and implement rapid response measures, including enhanced biosecurity using the USDA’s existing incentives programs, movement controls and contact tracing.
Stage 4: Demonstrating ongoing absence of H5 in dairy cattle in unaffected states
Once all dairy herds in a given state are considered to be unaffected, APHIS will continue regular sampling of farms’ bulk tanks to ensure the disease does not reemerge. Bulk tank sampling frequency will progressively decline as the state demonstrates continual silo negativity (e.g., weekly, monthly, quarterly if continually negative). If a state becomes affected, the USDA will reengage detection and response activities, and the state will return to Stage 3.
Stage 5: Demonstrating freedom from H5 in U.S. dairy cattle
After all states move through Stage 4, APHIS will work with the states to begin periodic sampling and testing to illustrate long-term absence from the national herd.
As states begin testing through the NMTS, and as they move through the five testing stages, their progress will be shared at USDA HPAI in Livestock Testing.
The USDA will work closely with states to determine each state’s status. “While the majority of states will enter the NMTS at Stage 1, we anticipate states with ongoing testing may meet the testing requirements described above in Stages 2-4,” the USDA said in the announcement.
The NMTS significantly furthers testing that has taking place since confirming the initial H5N1 infections in cattle in March 2024.
The USDA has provided H5 livestock testing free of charge through the NAHLN laboratory network. Prior to this, testing has been performed prior to the interstate movement of cattle; through the Dairy Herd Status Program; under state-required testing programs, prior to intrastate movement to fairs, exhibitions or sales as part of state testing programs; or for producers interested in learning the status of their livestock herds.
As a result of these tests, the USDA has received samples from each of the 48 contiguous states over the course of this outbreak. All confirmed positive findings have been reported through the APHIS website, and whole genome sequences of each detected virus uploaded to public databases.
“APHIS and state partners have seen significant success in responding to detections identified through state-level testing programs, and the NMTS builds on these efforts and will better identify the prevalence of the virus and guide response steps nationwide,” the USDA said in the announcement.
